1. Field of the Invention
This invention relates to a caulk for geological formations and mine stoppings. The caulk is especially suitable as a perimeter and void sealant for new and repair work to ventilation stoppings of coal mines.
2. Description of the Prior Art
Stopping devices are used to control and direct the flow of air through underground passageways and to seal off portions of a mine. The stoppings are often installed in mines so as to direct air flow to the working face and prevent loss of air flow through cross cuts and entries which are not being worked. In ventilating the mine, fresh air is delivered under pressure to the working face and often must travel a considerable distance between the mine opening and the face of the mine. If the stoppings separating the crosscuts and entries are not sufficiently air-tight, the losses will be such as to effectively reduce the velocity of the air at the mine face. It is not uncommon for a mine to lose more than half of its induced air through leaky stoppings and doors. Consequently, the dust and gases in the area being worked by the miners will not be effectively removed to the outside of the mine.
Conventional mine stoppings consist of walls constructed of concrete blocks and cement, and are not very airtight. These mine stoppings are sealed against air flow by coating the stopping face and sealing its perimeter with cementitious type caulks. Current cementitious caulks generally are composed of various inorganic aggregates, including glass fibers, in conjunction with portland cement, and are characterized by a number of deficiencies. Because these caulks are fragile and have limited adhesion to various substrates, such as trona ore, they often separate from these substrates when minor substrate movement occurs. Prior to application of these caulks, the pretreatment of mine formations, such as stopping perimeters, is usually specified and/or required to enhance bonding. The recommended pretreatment is high pressure washing to remove rock dust and dirt. This is a labor-intensive and time-consuming operation requiring a water source, a significant amount of equipment and costly delays before the sealing caulk can be applied to pretreated areas. Also, the caulk is mixed at the work site just prior to application. The procedure is labor intensive as all materials, i.e., bags of dry mix, water, mix containers, tools, etc., must be brought to the work site.
Further disadvantages of current sealants are their extremely short pot-life after mixing and the long time required after application for hardening (4-8 hours) and for the attainment of significant air and moisture resistant properties (in excess of 24 hours). Furthermore, the glass fiber often used is attacked by the high alkalinity of the hydrated portland cement, and therefore loses much of its tensile strength in just a few days. Another factor contributing to the high cost of using current caulk sealants is the need for large dry storage areas to accommodate the required raw material and equipment.
It would be highly desirable if an improved caulk for application to mine stoppings and like formations could be found to overcome the above and other disadvantages of the prior art, and result in the provision of highly airtight constructions which can resist air infiltration for extended periods of time.